1. Field of the Invention
The invention concerns an arrangement for operating a mobile terminal, for example selectively via a cordless system in a fixed network based on the DECT (Digital European Cordless Telecommunications) standard, or via a cellular mobile radio system based on the GSM (Global System for Mobile Communication) standard.
2. Discussion of Related Art
To an increasing degree many subscribers need to be able to telephone regardless of their location, both in a limited company district which is serviced by a cordless system, as well as from a car. Within the company district a subscriber usually uses a cordless telephone which is based on the DECT standard, and in the car a car telephone which is based on the GSM standard. To avoid using two different telephone devices, it is known to use a dual-mode hand set which can transmit and receive DECT as well as GSM signals, see DE 43 44 702 A1. Radio contact with the DECT system is preferred in this case because the DECT system has a technically better speech quality than the GSM system. Although a realization of the dual-mode hand set is possible, it takes a considerable effort however to adapt the different determinations of the standards to each other, such as for example speech encoding, keying, handover procedure and authentication of the mobile terminal. To comply with this requirement it is known to assign a so-called interworking unit to each DECT control station, see "Radio Show" brochure 3, 1996, page 24, Franzis Publishers GmbH, Feldkirchen.